Conventionally, a conical roller bearing is described in Patent Document 1. In addition, when a conical roller bearing is lubricated by grease, the conical roller bearing is lubricated by churning grease or lubricated by channeling grease depending on an application.
Here, oil content is more smoothly supplied to a raceway surface in the churning grease than in the channeling grease, while there is a problem that agitation resistance of grease increases and heat generation due to the agitation resistance also increases. On the other hand, it is advantageous in torque reduction because the channeling grease has small agitation resistance, while grease inside a bearing is splashed to the outside of the raceway at an initial stage of driving, so there is a problem that oil content supplied to the raceway surface reduces and it is disadvantageous in bearing life.